A pre-charged pneumatic (PCP) rifle releases compressed air to drive a projectile. A tank stores the compressed air. The tank has a threaded neck for connecting to a rifle. Cocking the rifle exposes a breech for manually loading a projectile. During firing, a hammer is released to strike a valve. Prior to being struck by the hammer, the valve is held closed by a spring and the pressure of the compressed air in the tank. When struck by the hammer, the valve opens briefly to release a burst of compressed air. The compressed air drives the projectile from the breach and through the barrel of the rifle.
Unfortunately, the tank must be removed from the gun for refilling after a limited number of firings (e.g., 25 to 40). The tank is usually filled from a high pressure air supply, such as a diving cylinder, or by recharging with a hand pump. Refilling requires use of special adapters to couple the tank to the diving cylinder or pump. Frequent removal and refilling is not only time consuming and laborious, but also risks damage to the threaded neck.
Determining when a refill is necessary can be difficult, particularly for rifles not equipped with pressure gauges. While a user may sense a lack of sufficient pressure as the tank is depleted, this method of pressure management is highly imprecise. Counting the number of shots is inconvenient, conducive to error and ineffective for a rifle with an undetermined number of prior shots from a tank. Additionally, neither of these methods enables a user to determine the pressure before the rifle is fired.
In some air rifles, the centerline of the tank is aligned with the centerline of the barrel. In such rifles, the tank doubles as a butt stock. However, because the tank is bulbous, it can interfere with aiming. A scope is typically mounted to such a rifle using high scope mounts. As the distance between the barrel and a high scope is substantial, aiming is compromised, resulting in frustration and fewer target hits. Lowering the height of the scope to bring the line of sight closer to the projectile path will result in discomfort. A shooter may have to cram his head onto the tank and crank his head at an extreme angle in order to aim through a low scope. Conversely, if the scope is mounted too high, not only will aiming be compromised but the shooter may find himself hovering over the tank, without his head touching it. Either case will induce unsteadiness as a shooter fights to acquire a sight.
The invention is directed to overcoming one or more of the problems and solving one or more of the needs as set forth above.